A conventionally known machine tool includes a cutting tool configured to cut a workpiece, rotating means configured to rotate the cutting tool and the workpiece relative to each other, feeding means configured to feed the cutting tool and the workpiece in a predetermined feeding direction, and vibration means configured to allow relative reciprocating vibration between the cutting tool and the workpiece.
An example of such a machine tool is described in United States Patent Publication No. 2014/0102268, published on Apr. 17, 2014. A control apparatus of the machine tool allows the machine tool to machine the workpiece by relative rotation between the cutting tool and the workpiece and by feed movement of the cutting tool toward the workpiece with reciprocating vibration.
The conventional machine tool is configured so that an operation instruction is issued by the control apparatus at a predetermined cycle. Therefore, the vibration frequency at which the cutting tool and the workpiece vibrate relative to each other is defined as a limited value attributable to a cycle during which the operation instruction can be issued by the control apparatus. However, the above vibration frequency is not considered in the conventional machine tool. Therefore, with respect to any number of rotations of the relative rotation, the reciprocating vibration may not be performed at any number of vibrations of the cutting tool relative to the workpiece during one rotation of the workpiece. Further, stripe patterns are generated on a machining surface of the workpiece when the cutting work is performed by reciprocatively vibrating the cutting tool, which may cause deterioration of the appearance of the machining surface of the workpiece.